فهرست مطالب

دانش آزمایشگاهی ایران - سال ششم شماره 3 (پیاپی 23، پاییز 1397)
  • سال ششم شماره 3 (پیاپی 23، پاییز 1397)
  • 44 صفحه،
  • تاریخ انتشار: 1397/08/20
  • تعداد عناوین: 6
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  • Farzane zamani, Rohullah Kashanaki Page 7

    MP-AES is the ideal instrument for people looking to transition from Flame Atomic Absorption Spectroscopy (FAAS) to another technique. By using nitrogen as the source gas for the plasma, running costs are greatly reduced, and by removing the requirement for hazardous nitrous oxide and acetylene safety is greatly increased. Additionally the higher temperature nitrogen plasma atomization/ ionization source improves detection limits, linear range, and long term stability, and allow the sample preparation process to be greatly simplified.

    Keywords: Cost, Safety, Detection Limits, Linear Range, Stability, Preparation
  • Mahshid Rahimifard, Maryam Yousefi, Mahmoud Naderi Page 15

    Fast protein liquid chromatography (FPLC) is a form of medium pressure chromatography originally developed for purifying proteins with high resolution and reproducibility. Its distinguishing feature is that the stationary phase is composed of small-diameter beads (generally cross-linked agarose) that are packed in glass or plastic columns and have high loading capacity. The FPLC system allows the use of a wide range of aqueous buffers (the mobile phase) and different stationary phases to perform the main chromatography modes (ion exchange, gel filtration, affinity and hydrophobic interaction, reverse phase). However, anion exchange and gel filtration chromatography are the modes most commonly used.

    Keywords: fast protein liquid chromatography, ionexchange, gel filtration, affinity, hydrophobicinteraction
  • Gholamreza Dehghani, Maryam khosravi, Mina Mohebbi Page 22

    The difficulties and limitations of imaging with scanning electron microscopy in high vacuum with some samples lead to manufacturing Environmental Scanning Electron Microscope (ESEM) or special detectors with the ability to work in low vacuum conditions. The vacuum rate inside the chamber in high vacuum SEMs, is approximately [10-3] Pa. The imaging in this condition could be done with appropriate quality. But despite of sputtering thick layer of golden coat, in some nonconductive specimens like Hydroxyapatite and porous Nano Silica, charging effect commonly occurs because of the porosity of the material. Some samples like organic wastes, pastes, binders (like oils), lubricants and other additives may be evaporated in high vacuum and imaging process will get into trouble. Also low vacuum usually is applied for biological samples and scaffolds due to their deformation in high vacuum.

    Keywords: Scanning Electron Microscope, lowvacuum, Secondary Electron
  • Parvin Hadian, Samira Ataei, Maryam Khorashadi Zadeh Page 26

    The atomic force microscopy (AFM) provides a powerful tool for providing images of biological samples from single molecules to living cells, allowing them to control and study. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM imaging in biology, various technological developments would be required to address certain limitations of the method. This has led to the creation of a range of new imaging modes, which continue to push the capabilities of the technique today. Here, we review the basic principles, advantages and limitations of the most common AFM bioimaging modes, including the popular contact and dynamic modes, as well as recently developed modes such as multiparametric, molecular recognition, multifrequency and high-speed imaging. For each of these modes, we discuss recent experiments that highlight their unique capabilities.

    Keywords: Atomic force microscopy, Force distance curve, Biology, Cantilever, Living cell